Phonetics is the study of sounds and the humanic voice. It is concerned with the actual properties of speech sounds (phones) as well as those of non-speech sounds, and their production, audition and perception, as opposed to phonology, which is the study of sound systems and abstract sound units (such as phonemes and distinctive features). Phonetics deals with the sounds themselves rather than the contexts in which they are used in languages. Discussions of meaning (semantics) do not enter at this level of linguistic analysis, therefore.

While writing systems and alphabets often attempt to represent the sounds of speech, phoneticians are more concerned with the sounds themselves than the symbols used to represent them. So close is the relationship between them, however, that many dictionaries list the study of the symbols (more accurately semiotics) as a part of phonetic studies. Logographic writing systems typically give much less phonetic information, although it is not necessarily non-existent. For instance, in Chinese characters, a phonetic is a portion of the character that hints at its pronunciation, while the radical gives semantic information. Characters featuring the same phonetic typically have similar pronunciations, but by no means are the pronunciations predictably determined by the phonetic; this is because pronunciations diverged over many centuries while the characters remained the same. Not all Chinese characters are radical-phonetic compounds, but a good majority of them are.

Phonetics has three main branches:

• articulatory phonetics, concerned with the positions and movements of the lips, tongue, vocal tract and folds and other speech organs in producing speech;
• acoustic phonetics, concerned with the properties of the sound waves and how they are received by the inner ear;
• auditory phonetics, concerned with speech perception, principally how the brain forms perceptual representations of the input it receives.